A computer network is a collection of interconnected computing devices that can exchange data and share resources. The Open Systems Initiative (“OSI”) model of a network comprises seven layers. A layer two (“L2”) network protocol may, for example, handle framing of data and interface between the higher layers and the physical layer. Ethernet is one example of a L2 communication protocol. Network switches are an example of L2 devices which participate in the exchange of data. Network switches connect a plurality of network devices to each other. A device connected to one port of a network switch is typically able to communicate directly with any other device connected to another port of that network switch.
Autonegotiation is the process by which two devices in communication select different parameters like maximum transmission rate, flow control, full-duplex or half-duplex, supported by both devices. For example, if one device supports a transmission rate of 1 Gb/s, but another device only supports up to 100 Mb/s, it may be possible for these two devices to communicate at a lower speed of 10 Mb/s, but transmission at the maximum transmission rate supported by both devices (i.e., 100 Mb/s in this example) would increase the speed with which the devices may share data, as well as increase network efficiency. Therefore, the devices would likely autonegotiate and attempt to communicate at the maximum transmission rate of 100 Mb/s.
Varieties of physical connections and data transmission rates exist for interconnecting network devices. Each class of connections may have a unique standard issued by the Institute of Electrical and Electronics Engineers (“IEEE”). For example, IEEE standards exist for various connection materials, such as fiber, copper, and twisted-pair, at rates of 10 megabits per second (Mb/s), 100 Mb/s, and 1000 Mb/s. These standards are important for developers of network devices, such as switches, hubs, and routers, so that the devices may autonegotiate a rate at which to exchange data between each other.
As standards evolve and new standards emerge, the specified interface format between the media access controller (MAC) and the physical layer (PHY) often changes. In some cases, an industry standard for achieving a high transmission speed, such as 1 Gb/s, may require a different physical interface format than the that of an existing standard for lower-speed transmission. Moreover, in some cases it may be desirable to utilize the physical interface format for the higher-speed communication even though the new standard has not yet been fully adopted or widely deployed. This may present challenges if, in order to comply with the standard, a devices is required to support auto-negotiation to lower speeds that require different physical interfaces.